Froth flotation of potassium chloride from sodium chloride



July 29, 1952 J. COLIN ETAL 2,604,988

, FROTH FLOTATION OF POTASSIUM CHLORIDE FROM SODIUM CHLORIDE Filed June17, 1947 7 Q7 l 1 CLEAR MOTHER UQUOR XXXXXX x x x I: 15- I X X X X X XX. X

PULP FRACTION OF'HIGH souo cement ATTORNEY 2,604,988 r I I YVOFEICEtino'jint Fromm vor POTASSIUM cHLoi Jules COIini RiblidrdBurr,

PE. 3 SO UM CHL I E 7 Roger Friedrich, and y it Xavier.- Herrgott,Mulhouse, HauteRhin, France,

assignors =;to Minesq: Domaniales mouse -B j M. r ta e? f F 19? e June17; 194

- 9 (llairiisl'j'wl.

:The present invention relates to mineralseparation by, flotation,andnwhile the illustrative. example herei-nafter-describew shows animport ant application of thejinventionito the separation of potassiumchloride inthe flotationtreatment: of sylvinitejpre-zthe invention hasutilityfor the 2 extraction of other ores.-

- ;.4 As 'conducive to :aclear understanding otthe invention, it isnoted that-where the, pl11p;f1fOm? which: :a valuable; component '5 isto: he ;.removed by theyfroth ormed in theflotation processghasrelatively low solid-content; a rich froth is formed but the efficiencyof extraction isgrelativelyqlow" and-much of the solid-to beextractedremains-inw the pulp. .On-the otherhand-wherethe .pulp hasrelatively highsolid content, while-extraction may e ne rl complete; thefroth; isi-n su' ic n lya;

i In France July 16, 1946 de Botasse F W-QQ @99 7, serial N'o."75 5,188

were; 7 l 1 I liVered-to t seco n agtanattsiata to tfi third stage foruse as pulp in the flotation cells f ther sn t v s a es 1 a. 1

In ;;.ca;rrying; out the proces suitable flotation reagent would beemployed which would be mixed with a suitable, frothing agentand thereis also which; latter i performsa selective action to pre preferahly=included asuitablemodifying agent vent adsorption orabsorption ofvaluable flotation such dross.

m llwj gd e t into-theteem-en he e would, he -include dexcessivequantities of dross v relatively costly; flotation reagent: and renderthe process relatively: uneconomical, especially so where f able, clayeyschist is presentjli treagent zbythe dross and to prevent neat-tones:

-Whicl -;wpuld= absorh considerable amounts of the selective andittakes-up considerableproportions;- I of solids intended-to berejected;Accord ng; @to -anothervfeature of the inven- It is among the objectsof? e .inventi 0 tiomthe ore slurry is permitted to settle so thatprovide a procedure and equipment capable; continuou o a ion which shallobv atea heglim V itations of flotation inpulp o fg mediumfiolid content; and which s l utilizesthe. nec ficx dva. tages and bviatethespecific disadvantages-iof -2 pulp ofrelatively .lowsol-id content onthe gene, handj and relatively high solid content on; the- 1 other;iniorder greatly :to increase the -'rate;and -z; completeness: ofextraction and to. do; so; With- :a minimum of waste of -flo-tationvreagent. z; -According.. to the, invention:=:from:atQ.ne 9 ts,

' aspects. the extraction process;- is conducted: in

three stages; rinv'olvingthree interconnected sets; of flotation cells.The first stage. utilizesqa gpulpof medium solid contentifromiiwhich thetailing v I ground down -toparticles of v1- m n. or less int'a liquidnedium,-inwhich grinding an important is separated into afractionofrelatively {high a solid contentand a c1ear:;liquor, the former ofwhichis utilized as piulp iin thezsecond stage and; the latter is usedin'therthirdistage. The -frothfrom' the, second stage is returned tothe-first; stage, from which the fro'tlrisin turn passed to;- the third"stage. and; the :selected component to, J be' extracted: from the-oreis -removed-.from; the froth in the latter stage.-=;' 7-;

According to a f-eature'ofr-the invention; 32 single settling tank v or"decanter; suppliedv from the tailing of the firstand-:third'stages-semester gravity separation into I two; fractions-, -aheavieror more concentrated thickened pulp-hand a= lighter supernatantliquor; jthfiq'iOlfmelfz bqi-lfigde-; :6

biewqbnr.

the lighter mud may be decanteda nd theresiduerela e1 stagef-o perationin the manner aboveref fr'd 7 1:0,,

the aptuc'atmi lbfths three l-1?h? wa he ni irsblr n; a, tank vieottom,;the mud beinguecant'ejd'and'the p eat-r s b n ved a S ts:

p n-for. entry into the first notation extraction process to sylviniteore,- substantially o -m ll. ths-st' d pulpflbn' tain glargel-y sodiumchloride and substantially completely freed :of potassiumchlorideswould' be! taken from thesecond stage. Before flotation suchsylvinite oreiwould part,;,o f{ the ,clay schists-of suchv S mmtstrewould go into suspension. The calcium and other heavy metal saltscontained in the-schists of t the mu ds thus formed- -tend toi reactwith -thlep flotation reagent to produce insoluble product-s ByaeasonOf-tithe .very large surface that these excessively fine particles ofclaypresent; the muds a ialos orio avery appreciable quantity ofl theflota-v tion ;reagent; =Which constitutes a substantial waste otvaluable material. W

the flotation treatment of sylvinite ore. That object is attainedaccording to the present invention by eliminating by simple separation,for example by decantation, much of the dross which is in the form offine particles in the clays; and the action of the heavy metals in thedross not removed by decantation is overcome by the introduction of amodifying agent into the flotation cells, which largely; prevents theflotation reagent from being adsorbed or absorbed by such metalcomponents of the dross.

It is another object of the invention to pre-' clude the formation ofminute crystals of "the salts to be extracted in the saturated-solutionthat constitutes the mother liquor in the extras tion from sylvinite orsimilari.ore,,since such-crystals would adsorb or absorb much crthenotation reagent with consequentwaste.

The formation of such minute "salt crystals is prevented by keeping thesalt-saturated mother liquor from cooling to such extent as to permitcrystallization. l .r w

In the accompanying drawings in which .is shown one of various possibleembodiments of the several features of the invention, l

tic-plan view oi theequip- C; each of which comprises a battery offlotation cells. Each cell may be of the conventionalconstruction,illustrativelyshown in -Fig. 3; and consistsof a tank- IQ; an impeller'I l therein having a vertical shaft i2' about which agitatingair isadmitted through tube' 'l3 to ca se setauon -re:

agent in thef tank, with or without auxiliary foaming agent enema-orwithout-modifying agent to form the frothywhichtogether with theextracted ma teria l is-skimmed off- 'f roni 'the theicollectof-troughMatone side oftop-into thetank. A v i According to the invention; thefirst stage of flotation inj'the battery her cells is conducted with iaxpulp of L moderate solidcontent'-and it p v moderately rich frothentraini'n'gimuchj y of the valuablecomponentto be'extract'ed;

The tailings from thefirst stageis then dischargedwherefrom through aconduit- 1 5 to be subjected to suitable thickeningffor discharge of thethickened pulp tothe second stage- B and or the :clear supernatantliquorto--the third-stage C.- :By virtue of the *relativelyhigh solidcon tent of the 'pulp' in'thes'econd stage; the-relatively small residueof valuable component re maining therein after flotation mthe firststage will be substantially completely recoveredand the V substantiallycompletely exhausted 'ta'ilings will be passedfofi through conduit; fromthe second The layer V delivered by conduit 18 back to the first stage Afor recycling therethrough. "The froth collecting at l9 in thefirst-stage is delivered-through conduit '28 to: the third stage 0;Since the pulpin Preferably-both of froth l I from-the second stage isth'e pulp of high'solid content in the second stage B and that oflowsolid con- 4 tent in the third stage C are derived from the first stageA after the extraction operation therein. This may be performed by theuse of a single decantation or separating tank 23 from which all thesolid particles which settle as a pulp to the bottom are conveyed byconduit 24 to the second stage B, while the clear mother liquorconstituting the supernatant fraction is passed by wayof conduit 26' tothe thirdstag'e: 01*? Stage C may be designated the re-cleaning stage,the supernatant clear liquor from the gravity separator 23 affording adilute pulp when conveyed to stage..C,.with low proportion of solid toliquid and hence-arich froth. Preferably also the taili'n'gs' fromsaidthird stage are returned by con- ;duit- 21 :back: to jthe settlingtank 23 for gravity ::separation-;in.:admiiiture with the tailings fromhusbythepperation set forth, a fair degree of extraction-occurs in thefirst stage A, substan- "tial;ly:completeyextraction occurs in thesecond the pulp of the valuable 'fstage-Bij and a heavy relativelystable froth in the third stageC is the agency for the removal from orecomponent to be extracted.

Preferably y the ore from: the grinding mill is pretreatedbeforedelivery into the flotation cells. Ta'this end the -mother liquorwitd-th ground ore forming agslurry is tlelivered into the'r tank28whichha's a conical bottom 29." I-h super I natant muddy water is'drawn oif as-in-the collecting trough 30 for clarification; whilethehe'avier residue is -=passed -through pipe "3 I for amnedecantationand washingyas shown;

or brineis preferably: passed through conduit 32 tothat level of tanlc33 (preferably with. an inclined": bottom fl) to' which the .liquorreaches;

thereby to rinse-'the mass. The rinse water witli the'debris passesofithrough g'utte'r as-ane' is urged by pump-'36;by' way of conduit 31 backtr scribed.

,While *th'e above system and mode' or operation has been defscribed'ingeneral -"-tern'1s and is-applicable' fo the treatment of ores l of awide va- 'riety;--1tf'finds a particularapplication, as'above noted' irithe extractionof potassium chloride from sylvinite ore.'Inthisap'plication it will be:

understood that the mother liquor would" beconcentrated solution orbrine: of the watersoluble components of sylvinite ore-largely of Ypd-ytass'ium chloride and sodium chloride;- The inc tation' reagentorcollecting agent would be a any of a variety or known compoundsselective for potassium' ch'loride such as amine acetates 'of the tformula RNH'ZHUiCCHadn WhichVR is a hydrocarbon radical havingpreferably between 16 and ieatoms-cr carbon, or sodium salts ofalkyl'sulphatesof the formula; R'SONa in. which R isia' hydrocarbonradicalhavingbetweenc and 12vat-iom's of-' carbon. TIieTlotation'reagent is *preferably mixed with a fr'othing agent-such. asoil'iof Eventhough pretreatment as above described;

is resorted to prior to flotation 'of sylvinitei ore, it will "beunderstood that substantial "quantities In a desirable embodiment;clearmother liquor "cells which willfrninert to such; dro' or albuminoids;bone glue, urea and tarch;-the latt e r being preferableforthet-reatment ofAlsatian For treatmentof,such sylvinite ore, a desirabletreating solution per ton. of unrefined slurry to be treated would'beIapproximja'tely as follows:

As the flotation reage'ntLlZiO gralmsofsodium salts-of alkylsulph'onates orfs'ulphates or alkyl or alcohol acetamides of theorm'ulas above specified.- I

As the frothing agent80 grams'of oil bf'pine-L As the modifyingagent-100 grams of starch.

In practice, if the mother liquor is saturated with salt, say at 25 0.,even a moderate drop of temperature overnight, say to 22 (3., wouldcause excess salt to crystallize in the form of very minute crystalswhich would present a very large surface area, thus leading to theabsorption or adsorption of much of the flotation reagent withcorresponding waste. To avoid such waste, the temperature of the motherliquor in the flotation cells is kept from dropping to such extent as topermit such minute crystals to form. It is of course not necessary tomaintain an accurate thermostatic control, but occasional reheating ofthe liquor would be adequate should the liq-.

nor in the cells become cool.

As many changes could be made in the above method and equipment, andmany apparently widely difi'erent embodiments of this invention could bemade without departing from the scope of the claims, it is intended thatall matter con tained in the above description or shown in theaccompanying drawings shall be interpreted as illustrative and not in alimiting sense.

Having thus described our invention what we claim as new and desire tosecure by Letters Patent of the United States is:

1. The method of separation by flotation of potassium chloride fromsodium chloride with a collecting agent selective for potassiumchloride, which comprises a first stage of flotation including the stepof floating, removing a froth concentrate, separating the tailings toremove therefrom a fraction of relatively high solid content leaving aliquor fraction, passing said froth concentrate from the first stage offlotation to said liquor fraction to provide a combined frothconcentrate and liquor fraction and performing another stage of frothflotation upon said combined froth concentrate and liquor fraction.

2. The method of separation by flotation of potassium chloride fromsodium chloride with a collecting agent selective for potassiumchloride, which comprises performing a first stage of flotation,including the steps of floating, removing a froth concentrate,separating the tailings from said first stage into a fraction ofrelatively high solid content and a substantially clear mother liquor,passing off the high solid content fraction and performing a secondstage of froth flotation thereon, and passing the froth removed fromsaid first stage to the substantially clear mother liquor segregatedfrom said first stage and performing a third stage of froth flotation onsaid combined froth concentrate and liquor fraction.

3. The method recited in claim 2 in which the froth from the secondstage is re-cycled through the first stage.

flotation with pulp of medium solid content, in-

cluding the steps of floating,removing a froth concentrate, removing thetailings" from the first stage and gravity separating'sai'd' tailingsintoa fraction of relatively high solidcontent and a substantially clearmother-liquor, passing off the high solid content fractionand 'performing'a second stag'e of froth flotation thereon, andpassingfthefroth-removed from the'ffirst stage of flotation to the substantiallyclear' mother liquor separated-from said first stage and performingatliird stage offrothflotation on said combined froth and liquorfraction. r

5. The method of separation by flotation of potassium chloride fromsodium chloride with a collecting agent selective for potassium chloridein three stages, which comprises a first stage of flotation with pulp ofmedium solid content, including the steps of floating, removing a frothconcentrate, removing the tailings from said first stage and separatingthe same into two fractions, comprising a thickened fraction ofrelatively high solid content and a substantially clear supernatantmother liquor, passing off the high solid content fraction andperforming a second stage of froth flotation thereon and passing thefroth concentrate removed from the first stage to the substantiallyclear mother liquor separated from said first stage, and performing athird stage of froth flotation thereon, removing the tailings from thethird stage and combining them with those from the first stage forgravity separation and recycling thereof.

6. The method recited inclaim 5 in which the froth from the second stageis re-cycled through the first stage.

7. The combination recited in claim 5 in which the mother liquor of thepulp is a saturated solution of salts in the ore and is heated a fewdegrees to a temperature to dissolve the minute crystals of such salts.

8. The method of separation of a high grade concentrated product ofpotassium chloride from mud containing ground ore of particle size ofone millimeter or less in diameter with substantial components of sodiumchloride and potassium layer of muddy water, decanting the muddy water,rinsing the settled ore particles with brine and subjecting the thusrinsed product to froth flotation in appropriate reagent for recovery ofsuch high grade of concentrated product of potassium chloride, saidflotation being conducted in three stages comprising a first stage withpulp of medium solid content, a second stage with pulp of relativelyhigh solid content, and a third stage with pulp of relatively low solidcontent and after flotation in the first stage, subjecting the tailingsfrom the first and third stages to thickening and feeding the thickenedtailings to the second stage and the clear mother liquorto the thirdstage.

9. The combination recited in claim 8 in which the mineral carryingfroth is re-cycled from the second to the first stage.

J. COLIN.

R. BURR. R. FRIEDRICH. X. HERRGOT'I'.

(References on following page) 11::REFERENG SCI'E The foilowirigreierencesf are of reoord in the file'of this patenti I UNITED STATESPA'IENTS Number Tartaron :Septp21, 1943 Number Name ,Date Ferris -Dec.14,1943 Ferris Feb. 1, 1944 Cole Dec. 5,1944 Cole Dec.- 26, 1944 MeyerApr. 22-, 1947 Greene 1423713, 1947 OTHER REFERENCES American Instituteof Mining and Metallurgiw cal Engineers, contribution No. 86, by John T.Crawford (c) 1935 'llrpages.

Taggart, Handbook of Mineral Dressing, 1945, section 2, pgs-.-44-45.'

Taggart, Handbook of Mineral Dressing, 1945, section 12, page 98. 9 j

1. THE METHOD OF SEPARATION BY FLOTATION OF POTASSIUM CHLORIDE FROM SODIUM CHLORIDE WITH A COLLECTING AGENT SELECTIVE FOR POTASSIUM CHLORIDE, WHICH COMPRISES A FIRST STAGE OF FLOTATION INCLUDING THE STEP OF FLOATING, REMOVING A FROTH CONCENTRATE, SEPARATING THE TAILINGS TO REMOVE THEREFROM A FRACTION OF RELATIVELY HIGH SOLID CONTENT LEAVING A LIQUOR FRACTION, PASSING, SAID FROTH CONCENTRATE FROM THE FIRST STAGE OF FLOATION TO SAID LIQUOR FRACTION TO PROVIDE A COMBINED FROTH 